Mustafa Seidaliev is a human rights defender working on the protection of Crimean Tatars rights following the annexation of Crimea in 2014. Since 2017 he works as a public defender, supporting lawyers in cases before the courts and representing Crimean Tatars in civil proceedings and court cases. In 2019 Mustafa Seidaliev joined Crimean Solidarity. Crimean Solidarity monitors and documents human rights violations, provides legal aid, observes trials, and provides various types of assistance. Crimean Solidarity focuses mainly on providing support to the Crimean Tatar community, which has been particularly targeted by the Russian authorities. In June 2019, the human rights defender was detained in Moscow, Russia, alongside 40 other representatives of the Crimean Solidarity movement peacefully protesting the prosecution of Crimea Tatars based on alleged extremism charges.